Reversible electromagnetically controlled drive device

ABSTRACT

An electromagnetic servounit comprising two drive units connectable through a speed reducing unit to an output shaft, each drive unit comprising telescoped magnetic drive and driven members with an air gap therebetween and energizing coils for selectively setting up a magnetic flux path across the air gap of each unit whereby the output shaft is driven solely by either drive unit or jointly at a speed and torque proportional to control signals applied to both drive units.   D R A W I N G

United States Patent Inventor Robert M. Hulle Calabasas, Calif.

Appl. No. 808,551

Filed Mar. 19, 1969 Patented Jan. 26, 1971 Assignee Clary Corporation San Gabriel, Calif. a corporation of California REVERSIBLE ELECTROMAGNETICALLY CONTROLLED DRIVE DEVICE 2 Claims, 2 Drawing Figs.

U.S. Cl 310/101,

310/98, 310/99, 310/103 Int. Cl H02k 49/06 Field of Search [56] References Cited UNITED STATES PATENTS 2,908,834 10/1959 Munson 310/105 2,912,607 11/1959 Duncan 310/99 3,283,188 11/1966 Edick 310/105 FOREIGN PATENTS 20,463 1901 Great Britain 3 10/ 101 Primary ExaminerD. X. Sliney Att0rney-Fred N. Schwend ABSTRACT: An electromagnetic servounit comprising two drive units connectable through a speed reducing unit to an output shaft, each drive unit comprising telescoped magnetic drive and driven members with an air gap therebetween and energizing coils for selectively setting up a magnetic flux path across the air gap of each unit whereby the output shaft is driven solely by either drive unit or jointly at a speed and torque proportional to control signals applied to both drive units.

PATENTEU Jmzs um SHEET 2 BF 2 INVENTOR 05527 M HULL/f ATTOAP/VE)/ REVERSIBLE ELECTROMAGNETICALLY CONTROLLED DRIVE DEVICE This invention relates to reversible servodrive devices for driving a load in either direction at different speeds and by different amounts. Such devices are used in automatic pilots for aircraft, antenna rotating devices, tuning devices. ordinance aiming devices, etc., wherein it is desirable to drive such mechanisms by power and under the influence of electrical control signals.

Heretofore, servodevices of the above type have generally comprised reversely driven and selectively operable friction or powdered iron" clutches. Although such devices work generally satisfactorily. the frictional surfaces tend to heat up and wear under rigorous operating conditions so that frequent adjustment is necessary and the life of the servodevice is relatively short. Also, because of heating conditions, such devices often do not operate consistently.

It therefore becomes a principal object of the present invention to provide a servodevice of the above type in which no friction or powdered iron clutches are used.

Another object is to improve the reliability and life of a servodevice of the above type.

Another object is to provide a relatively simple and compact servodevice of the above type.

Another object is to provide a highly sensitive servodevice which may be selectively controlled by one or another or both of opposite direction control signals.

A further object is to provide a highly efficient servodevice which will be self-braking when no control signals are received.

The manner in which the above and other objects of the invention are accomplished will be readily understood on reference to the following specification when read in conjunction with the accompanying drawings, wherein:

FIG. I is a longitudinal sectional view through a servounit embodying a preferred form of the present invention.

FIG. 2 is a transverse sectional view taken substantially along the line 2-2 of FIG. 1.

The servodevice comprises two separable housings l and 11 suitably attached together. A motor 12 is attached to the right-hand wall 13 of the housing with its output shaft 9 extending through an opening in the wall and terminating in a gear 14. The latter meshes with a larger gear 15 fixed on a shaft 16 which is rotatably supported by bearings carried in the wall 13 and in a second wall 17 of the housing 10.

A pinion 18 attached to the shaft 16 meshes with a gear 20 formed integral with a cup-shaped drive member 21 of the drive unit 19, the member 19 being rotatably supported by a tubular shaft 22 through ball bearings 23. The member 21 includes a hub 24 and a cylindrical outer flange 25. The drive unit 19 also comprises a cup-shaped driven member 26 having a hub 27 and a cylindrical flange 28 located in telescoped relation with the flange but separated slightly to form an air gap therebetween. Driven member 26 is supported in fixed relation to the shaft 22 by an annular support member 30.

Both the driving member 21 and driven member 26 are formed of soft iron or other magnetic material having little magnetic remnance, and in order to set up a magnetic flux path through the same, an electromagnetic energizing coil 31 is suitably secured to the hub 27 of member 26 and extends over the hub 24 but is spaced slightly therefrom the latter to form an air gap 32.

As seen in FIG. 2, the flanges 25 and 28 are slit longitu dinally at 33 in several places therearound to form separate magnetic pole pieces, the pole pieces in flange 25 cooperating with the pole pieces in flange 28.

A second drive unit 34 is located directly to the left of drive unit 19 and is similar in construction. having a drive member 35 and a driven member 36, the latter being secured in fixed relation to the driven member 26 by nonmagnetic connectors 37 and supported by the shaft 22 through an annular member 38.

Means are provided for rotating the drive member 35 in a direction opposite to that of drive member 21, and for this purpose a drive gear 40 is formed on member 35 and meshes with a pinion 41 carried on a shaft 42 on which is also carried a pinion 43 meshing with the pinion 18. The pinion 43, however, is offset axially so that it does not mesh with the gear 20.

A coil 44 is secured to the hub ofdriven member 36 and is connected by conductors 45 and 46 to respective slip rings 47 and 48 carried by the shaft 22. Such rings are suitably insulated from each other and are engaged by brushes 50 for transmitting electrical control signals to the coil 44. Likewise, the coil 31 is connected by conductors 45 and 51 to slip rings 47 and S2 to receive control signals independently of the coil 44.

The shaft 22 is supported by bearings 53 and terminates in a gear 54 which meshes with a gear 55 journaled in bearings 56 carried by an annular wall member 57 mounted in the housing part 11. The gear 55is secured to a planet gear carrier 58 by a bolt 60. The carrier 58 rotatably supports a planet gear 61 which meshes with a pair of internal gears 62 and 63. The former is integrally attached to the housing part 11 and the late latter is formed integral with an output drive shaft 64 which is rotatably mounted in a bearing 65 carried by a wall 66 of the housing part 11.

The gear 63 has one less tooth than the gear 62 so that as the planet gear 61 is carried in an orbit about the axis of gear 55 and shaft 64, the latter will slowly advance relative to gear 55.

A shaft position and speed indicating device 67 is suitably mounted in the housing part 11 and is entrained through gears 68 with the output gear 63.

The motor 12 is preferably driven continuously in one direction at its most efficient speed so as to obtain a maximum torque output. Application of an electric control signal to either ofthe coils 31 and 44 creates a magnetic field across the air gap of the respective driving and driven members to magnetically couple the same and thereby transmit a constant torque to the output shaft 64 in the appropriate direction and at a greatly reduced speed. Obviously, the length of the control signal will determine the angular movement of the shaft 64 and because of the relatively high speed reduction provided by the gear unit 61, 62, and 63, a self-braking effect will occur to arrest the output shaft upon cessation of the control signal and thus prevent the driven device from driving the shaft 64.

Of considerable importance is the fact that the speed and torque output of the shaft 64 may be varied without changing the speed of drive motor 12 from its most efficient operating speed and this is effected by concurrently applying voltages of different levels to both coils 31 and 44 whereby the magnetic coupling effect-of one drive unit is different from the other, resulting in an output speed and torque which is proportional to the difference between the levels of the control signals. Thus, also, by applying a greater voltage to one or the other of the coils, the direction of rotation of the shaft 64 may be reversed. Obviously, maximum output speed and torque may be accomplished by applying control signals to an appropriate one of the coils only'at a time.

It will be noted that the housing part 10 may be readily removed from part 11 for servicing or replacement and replaced with another housing part without having to dismantle any of the gears or other operating parts.

Further, since no frictional drive forces are involved, no appreciable heating will occur and therefore the unit will produce consistent output characteristics over long periods of time, regardless of the frequency at which reversals are made. Also, since the torque is transmitted solely by magnetic flux, a smooth yet substantially instantaneous reversal of the drive torque may be accomplished at relatively high frequencies.

I claim:

1. A reversible electromagnetic drive device comprising a driven shaft, driven member of magnetic material carried by said shaft:

drive members of magnetic material supported by said shaft for rotation relative thereto and relative to each other;

each of said drive members having a cylindrical flange extending in telescoped relation to a cylindrical flange on a respective one of said driven members whereby to form a first air gap therebetween;

each of said driven members and its.respective said drive member having adjacent hubs;

an electromagnetic coil carried by each of said driven members, and surrounding both said adjacent hubs;

said coil being secured to one of said hubs and spaced from the other of said hubs to form a second air gap;

said coil being effective to set up a magnet flux through a respective said drive and driven member and across said respective first and second air gaps; and

means for rotating said drive members in opposite directions.

2. A reversible electromagnetic drive device comprising a first housing having an end wall at one end thereof:

a second housing having a wall at one end thereof and open at the opposite end;

said open end of said second housing being removably secured to said end of said first housing;

a drive shaft rotatably supported in said first housing and extending through an opening in said end wall;

a motor supported in said first housing;

said motor having a motor shaft extending through an opening in said end wall;

meshing gears on said motor shaft and said drive shaft;

said gears being located in a said second housing;

a driven shaft rotatably supported in said first housing;

said driven shaft extending through an opening in said end wall;

a pair of normally inoperative electromagnetic drive devices supported by said driven shaft in said first housing;

means operable by said drive shaft for rotating said electromagnetic drive devices in opposite directional;

means for energizing one or the other of said electromagnetic drive devices whereby to rotate said driven shaft in either of opposite directions;

a drive gear on said output shaft and located in said second housing;

a gear transmission unit supported in said second housing;

and

said transmission unit including a driven gear meshing with said drive gear. 

1. A reversible electromagnetic drive device comprising a driven shaft, driven member of magnetic material carried by said shaft: drive members of magnetic material supported by said shaft for rotation relative thereto and relative to each other; each of said drive members having a cylindrical flange extending in telescoped relation to a cylindrical flange on a respective one of said driven members whereby to form a first air gap therebetween; each of said driven members and its respective said drive member having adjacent hubs; an electromagnetic coil carried by each of said driven members, and surrounding both said adjacent hubs; said coil being secured to one of said hubs and spaced from the other of said hubs to form a second air gap; said coil being effective to set up a magnet flux through a respective said drive and driven member and across said respective first and second air gaps; and means for rotating said drive members in opposite directions.
 2. A reversible electromagnetic drive device comprising a first housing having an end wall at one end thereof: a second housing having a wall at one end thereof and open at the opposite end; said open end of said second housing being removably secured to said end of said first housing; a drive shaft rotatably supported in said first housing and extending through an opening in said end wall; a motor supported in said first housing; said motor having a motor shaft extending through an opening in said end wall; meshing gears on said motor shaft and said drive shaft; said gears being located in a said second housing; a driven shaft rotatably supported in said first housing; said driven shaft extending through an opening in said end wall; a pair of normally inoperative electromagnetic drive devices supported by said driven shaft in said first housing; means operable by said drive shaft for rotating said electromagnetic drive devices in opposite directional; means for energizing one or the other of said electromagnetic drive devices whereby to rotate said driven shaft in either of opposite directions; a drive gear on said output shaft and located in said second housing; a gear transmission unit supported in said second housing; and said transmission unit including a driven gear meshing with said drive gear. 